Printed circuit edge connector



P. r. HAHN ETAL `PRINTED CIRCUIT EDGE CONNECTOR I Oct. 22, -1963 3Sheets-Sheet 1 Filed Dec'. 20. 1960 `g\ L Paul NVENTOR. T Hahn andGilbert C. Sitz y.llllzwhd Illl.

IT EDGE CONNECTOR PRINTED QIRCU Filed D60. v20. 1960 l5 Sheets-Sheet 2Gibert C. Sat-L f f INVENTOR.

Pau) T Hahn and NI Iullll |l| 'Il Illlllll .H" I v I l I I I I l IlIII-ll I d .HHUHHHMT N'MHWNHHIHMl IHHM@ om mm. om Q ILT@ mh J@ .NQ mw.om

.0t.22,19 63 P.T.HAHNETA| *3,107,961

' PRINTED cIRcUIT EDGE- CONNECTOR Filed Dec. 2o. 1960 Y l s sheets-sheets 9e e5 F6 65 '(76 96 :35:: ::7 7a 54 57 6&1 72.

y 9a /6 A gfm/ Oab |02 loo INVENT'oR. Paul T Hohn and Gilbert C. Sitz:-

United States Patent O 3,107,961 PRNTED CiRCUlT EDGE CGNNECTOR Paul T.Hahn and Giihert C. Sitz, Harrisburg, Pn., assignors to AMPIncorporated, Harrisburg, Pa. Filed Dec. 2i), 19e-9, Ser. No. 77,067

9 Claims. (Si. 339-17) p This invention relates to multiple contactconnectors for disengageably connecting two groups of conductors witheach other. The embodiments of the invention herein disclosed areparticularly intended for use with printed circuit boards, however, theprinciples of the invention are equally applicable to usage with otherpanellike devices having conductors thereon.

The Widespread adoption of printed circuit Wiring techniques has givenrise to the development of connecting devices, commonly called edgeconnectors, for disengageably connecting the conductors on the boardwith other conductors which are external to the board. Most of thepresently known types of edge connecting devices comprise an insulatingblock having an opening or trough -therein for reception of a portion ofthe edge of the board. A plurality of relatively small spring oontactsare mounted in the block and extend into this trough. These contacts arearranged in a manner such that upon insertion of the board, the contactsengage, and establish electrical contact with, the conducting paths onthe board. Usually, the contacts are resiliently pressed against theinserted board so that a contact force is established between thecontacts and the conducting paths of the board thereby to ensure anelectrical connection having a satisfactorily low resistance. A furtherfeature of the presently available edge connectors is that the connectorassembly is clamped to the board by the gripping action of theelectrical contacts themselves so that these contacts perform both theelectrical function of establishing the electrical contact with theconductors and the mechanical function of clamping the connector to theboard.

This prior art arrangement is satisfactory under many circumstances buthas some inherent disadvantages which can be explained as follows: Theboard obviously must be clamped by the spring contacts with suiiicientforce to hold the parts together and, preferably, this force should berelatively high in order to prevent relative movement between the boardand the connector block if either `of these parts is jarred or vibrated.The effect of vibration is particularly important since `if either theblock or the board should vibrate, the engagement of the individualcontacts with the conductors on the board might be intermittently brokento the detriment of the electrical function of the assembly. However,the contact force which each of the individual contacts exerts upon theconducting paths of the board should not be unduly high since increasingthe con-tact force beyond a certain level does not significantly lowerthe resistance of the contact interface but kdoes substantially increasethe wear on the contacts and conductors when the board and block areassembled Ito each other. This wear problem assumes an increasedimportance if the contacts or conductors are plated, as is common, withgold or tin since, a high contact force will cause the plating to berapidly worn olf as the contacts slide over the conductors when theboard is assembled to `the connector. Thus, with this prior artarrangement, a compromise contact force must be selected which may beunduly high from the wear standpoint but which may be barely adequateand less than optimum from the mechanical standpoint of clamping theboard and block together.

The design problem of these prior art type boards is further complicatedby the practical diiculty of obtaining this compromise contact force. Toillustrate, conventional printed circuit boards usually do not conformto precise thickness tolerances but, because of manufacturinglimitations, may vary in thickness Aby as much as 110%. Thus, if theedge connector is manufactured to accept a board having some givennominal thickness, the insertion of a relatively thick board (10%thicker than the nominal thickness) will result in extremely highcontact pressures with high attrition of the contact plating uponinsertion of lthe board. If the board happens to be relatively thin butstill within the tolerance limits, on the other hand, the board Iand.connector will not be clamped together with the requisite degree ofrigidi-ty.

It is among the objects of the present invention to obviate some of theforegoing shortcomings of prior art edge connectors.` More specifically,itis an object of the present invention to provide an edge connector orthe like in which the means for mechanically securing the board to thepanel is independent lof .the contacts in the connector block. A furtherobject is to provide an edge connector which can be assembled to panelsof varying thickness without changing the contact force exerted bythespring contacts in the connector on the conductors on the panel. A stillfurther object is to provide an edge connector forv printed circuitboards which has spring contacts arranged in a manner such that thesespring contacts will be resiliently loaded or deflected by the sameamount by boards of varying thickness.

These and other objects of the invention are achieved in one preferredembodiment comprising a block having n, a recess or trough for thereception of a portion of the edge of a printed circuit board. One ofthe longitudinal sidewalls of the trough has barriers or ledges thereonat spaced intervals and the contacts, which are mounted in the block,have iiexible ends which extend into the spaces between these barriers.The contact portions of the contacts (i.e. the surface portions whichengage the conductors on the board) are normally disposed outwardly ofthese barriers with respect to the sidewall of the trough so that uponinsertion of the board, these contacts are flexed and the contactportions are moved relatively towards the sidewall until the contactinterfaces are in alignment with the barriers. The mechanical clampingof the edge connector to the board is achieved by means of a clampingmeans which presses the board against the lbarriers described above.With this arrangement, theA clamping force is transmitted through theboard and to the barriers so that the contacts could be removed from theconnector block and the parts would still be secured together.

The invention is applicable to boards having conductors on only one sidethereof and to printed circuit boards having conducting paths on bothsurfaces. ln the latter case, the dielectric bloc'k is advantageouslyformed in two sections, each section having a recess so that a trough isdefined when the sections are assembled in face-to-face relationshipwith each other. These two sections are resiliently biased towards eachother so that upon insertion of the board, they are in effect, wedgedapart by the board against the force of the resilient means. Again, `thesections of the block each have barriers and the contacts are disposedbetween these barriers. Upon assembly of the connector to the edge ofthe board, the edge of the board is clamped between the barriers of theKtwo sections of the block.

In the drawing:

FIGURE l is a frontal view of one embodiment of the invention which isadapted Ifor usage with printed cincuit boards having conductors `on`only one side thereof.

FIGURE 2 is a view similar to FIGURE 1 showing E the positions of thepar-ts after insertion of an edge portion of a printed circuit board.

FIGURES 3 and 4 are views taken along the lines and looking in thedirection of the arrows 3--3 and 4 4 respectively of FIGURES l and 2.

FIGURE S is a perspective View showing a connector of the type shown inFIGURE l in assembled relationship tothe edge of a printed circuitboard.

FIGURE 6 is a frontal view of an alternative embodiment of the inventionintended for usage with printed circuit b-oards havin-g conductors onboth sides thereof.

FIGURE 7 -is a perspective view of the embodiment of FIGURE 6 andshowingV -a printed circuit board in alignment with the ltrough of theblock.

FIGURE 7A is ,a fragmentary perspective exploded view of the rear sideo-f the embodiment of FIGURE 6.

FIGURE 8 is a fragmentary view similar to FIGURE 6 but showing thepositions of the plants after insertion of a printed circuit board.

FIGURE 9 is a view taken along the lines 9 9 of FIGURE 8.

FIGURE l is a vie-w taken along the lines 111.46 of FIGURE 6.

FIGURE l1 is a view showing another embodiment of the invention.

FIGURE l2 is a view similar to FIGURE ll but showing the positions ofthe parts after insertion of fthe printed circuit board.

The embodiment of the invention shown in FIGURES 1-5 is -intended forusa-ge with the conventional printed circuit board l@ having conductors-12 on one side thereof. As shown in FIGURE 5, these conductors extendto the edge of the board and between notches 11 which are adapted toreceive the sides of connector bloicli 2.

The block 2 has a rear surface 4 and .a front surface 6 in which thereis a trough-like ope-ning 8 into which the edge of the board is adaptedto be inserted. Advantageously, the upper edge and a portion of the sideedges of this trough are beveled las shown at 14 to facilitate theinsertion of the board. The upper sidewall 17 of the trough, as viewedin FIGURE l, is provided with evenly spaced barriers or ledges 16 havingbearing surfaces 18 facing the opposite sidewall 2S of the block andlying in a plane which extends, in the disclosed embodiment, parallel tothe plane of the sidewall 17. A plurality of electrical contacts 20 aremounted in the block and yhave end portions 22 extending from the rearsurface 4 for attachment to wires (not shown).

The opposite ends 24 extend 4through the surface 19 of the trough andbetween adjacent barriers. The contact portion of the particular type ofcontact shown in the drawing has a generally triangular end 26, the apexof which normally is located inwardly (relative to the trough) of theplane defined by the .bearing Vsurfaces 1S. This particular type offcontact maybe form-ed from solid stock as by rolling or coin-ingalthough the principles of the invention are not limited to this form ofcontact. The important structural relationship of the contacts to, theblock is that the -apices of the contact portions are normally disposedinwardly of the plane of the bearing surfaces 18 so that upon insertionof lan edge portion of a board into the trough, the ends 24 of thecontacts will be exed only by the amount necessary to move these apices26 into the plane of the bearing surfaces 8.

The lower portion of the trough-like opening as viewed in FIGURE l isenlarged as shown at 3G and a Igenerally channel-shaped clamping plate32 is positioned in this portion of the trough. This plate has a flange34 extending from one of its sides and into an elongated recess or`groove 36 in the surface 19 of the trough 8. The opposite side of theplate has an apron 37 which extends downwardly, -as viewed in FIGURES 1and 3, towards the side 28 of ythe trough.

A spring 318 is inte-rposed between the underside of pla-te 32 and theside 2S of the trough and normally form of spring may be utilized, thedisclosed embodi t ment being an undulating leaf spring having twonode-s 40 upon which the underside of the plate rests. The ends of thisspring are lodged ybehind ledges 42 which form part of the dielectricblock so that after assembly, kthe spring and the apron will be retainedin the positions shown in the drawing.

As shown in FIGURE l, fwhen the parts are in their normal positions andbefore insertion of a printed circuit board, the upper surface of theplate 32 abn-ts the reentrant surf-aces 44 of the trough and is pressedthere'- against by the spring 38. Also, the contact tip portions 26 ofthe contacts are disposed inwardly of the trough with respect to .theplane of these bearing surfaces. Upon insertion of an edge portion of aprinted circuit board, the plate 312 is biased downwardly, 'as viewed inFIG- URES l and 2, so that a slight gap 45 (FIGURE 2) exists between theedge portions of the apron andthe rcentrant surfaces 44. The boarditself is clamped between the upper surface of the plate 32 and thebearing surfaces 18 of the ledges or barriers while the contacts areflexed as shown in FIGURE 4 until the contact tips or apices 26 aremoved into the plane of the bearing surfaces and towards the surface ofupper sidewall v17.

,In order to achieve all of the benefits of the inven-v tion, the forceexerted by the spring 38 on the printed circuit board should exceed thetotal force exerted on the board by all of the contacts 23, preferablyby -a substantial amount. T0 illustrate lthis point, if it is assumedthat ten contacts are provided in a block of the type spring 36 shouldbe of a stiffness such that it will exert Y a force of more than 5 lbs.,eg., about l() lbs., on the board after insertion. `If this relationshipbetween the stiffness of the spring and the stiffness of the contacts ismaintained, the board 10 will be clamped between sur-L faces 1S andplate 32. If the spring 38 is not sufficiently strong to overcome thestiffness of .the contacts, however, it is possible that the board willnot tbe so clamped but will merely be held between the contacts and theplate 32.

The several advantages of the invention can be appreciated from aconsideration of the manner in which the printed circuit board isclamped to the block 2 and the manner in which the contacts are flexedor resiliently deformed upon insertion of the board. It will be apparentfrom FIGURES 2 and 4 that if the contacts werevremoved from the block,the board would still be clamped between plate 32 and the bearingsurfaces 18 since the v contacts themselves are not relied upon for themechani-` cal clamping of the board. Obviously then, the board f can beclamped very firmly, if desired, by merely using an extremely stiffspring 38 and lthis arrangement would be desirable if the connector wereintended for usage in an environment where substantial vibration ispresent.

Alternatively, if the connector is intended for usage undercircumstances where substantially no vibration will be encountered andif a low insertion force is preferred, a

relatively weak spring can be employed, however, the spring should besufficiently stiff to overcome the tacts as explained above.

An added advantage of the arrangement shown is that printed circuitboards are not ordinarily manufactured to extremely close tolerance butwill vary in thickness by a substantial extent. The clamping plate andspring in combination with the bearing -surfaces 18 permits connectorsin accordance with the invention to adapt themselves Ito any reasonablevariation in board thickness so that the use of a connector inaccordance with the invention does not require the use of a preciselydimensioned printed circuit board.

An equally important advantage of the invention is COIly that thedetiection of the end portions 24 ofthe contacts, and therefore thecontact force, is controlled within eX- tremely precise limits. Thecontacts themselves can generally be assumed to be dimensionally uniformand can be assumed to conform to relatively precise dimensionaltolerances. if each Contact is located within the dielectric block witha reasonable degree of precision, the apex 26 thereof will be preciselypositioned at a fixed distance from the plane of the bearing surfaces18, and upon ine sertion of the printed circuit board this contact apexcan move only the amount of this distance. The ilenure of the contactportion -24 is therefore precisely controlled and, since this tlexuredetermines the contact force, the amount of contact force between thecontact apex 26 and the path i2 of the printed circuit board is likewiseprecisely controlled. This lfeature is of considerable importance sincethe contacts 26 are usually relatively short so that a slight change inthe amount by which they are deflected upon insertion of ythe board willresult in a fairly substantial change in the amount of contact pressureestablished. As pointed out above, the contact force should be onlysufficiently high to establish a low resistance electrical Contact butshould not be unduly high because of the plating wear problem. Obviouslythen, precise control of this contact force, to achieve the optimum, isan important achievement of the present invention.

An additional desirable feature of the disclosed ernbodiment is that asubstantial amount of ilat bearing surface is provided, by virtue ofbearing surfaces 18, between the block and the board. The existence ofthis bearing interface prevents accidental rocking of either of theparts relative to the other; in other words, the board is held betweeniiat :gripping surfaces 1S, and the surface of plate 32, and is notgripped only by the limited contact surface of the contacts themselves.

FIGURES 6-l0 show an alternative embodiment of the invention intendedfor usage with printed circuit boards of the type shown at 46 havingconducting paths i3 on both of their faces. The embodiment of FIG- URE 6comprises a pair of dielectric blocks Si), 52 which are substantiallysimilar in construction. In the description which follows, only theblock Si? will be described in detail and the corresponding parts of theblock 52 will be identied by the same reference numerals as those usedin conjunction -with the block 5t? but differentiated by means of primemarks.

Block section Sii has an open sided groove or recess 54 which extendsinwardly from two of its adjacent sides so that when this block isplaced against its counterpart 52, the two recesses 5d, 54 dene atrough-like opening for reception of an edge portion of the board. Theedges S of the block are beveled, as with the previously describedembodiment, to facilitate insertion of the printed circuit board. Thesidewall S7 of the recess is provided with spaced barriers or ledges 5Ssimilar to the barriers I6, and having coplanar bearing surfaces eil.Contacts d2, which in this instance are formed from sheet metal, aremounted in the block and have wire receiving portions di extendingthrough the rea wall 66. The opposite ends ed of the contacts extendinto the recesses 5d and into the spaces between adjacent ledges 6i).The contact portions 7G of the contacts are again disposed out--\vardly, with respect to the recess sidewall, of the plane delined bythe bearing surfaces 6ft. It will be appreciated that the arrangement issubstantially similar to the arrangement of parts in the embodiment of`FIGURES 1 5 and that the contact portions 7@ of these contacts areadapted to be moved relatively into the plane of the bearing surfacesupon insertion of the printed circuit board.

An ear 72 is provided on each side of block section S and this ear has agenerally cylindrical surface 74 which is adapted to receive the surfaceof a rivet or the like as described below. A flange 76 extends from theface 7S of the block and functions as a stop or retaining means for aleaf spring 8d. This spring has nodes S2 which normally bear against thetop surface 83 of the block. 'Ihe ends `Se of the spring are bent atright angles to the central section thereof and terminate in hooks 86.On one of the ends of each spring, one hook 86 is provided while twohooks are provided on the other end.

The hooked ends 36 of the block 5d are interdigitated with the hookedends d6 of the block 52 to dene a generally cylindrical surface and acylindrical pin or rivet `S8 is provided between these hooked ends tohold the parts together. The ends of these pins are hanged as shown at9d, as by upsetting, so that they will be held in the positions shown inFIGURE 7. The dimensions of the springs are such that the two blocksnormally abut each other at their edges 92. The block sections arc,however, capable of relative movement away from each other against theforce of the springs Si), 86. Advantageously, the opposed surfaces ofthe blocks 50, 52 have keying means in the form of a projection 94 andcomplementary recess so that they cannot be transversely or laterallymoved with respect to `each other.

In use, the printed circuit board 46 having the conducting paths d8 oneach of its surfaces is inserted into the trough `defined by therecesses 74, 74. The thickness of Ithis board is slightly greater thanthe distance separating lthe corresponding bearing surfaces 66, 60 ofcorresponding ones of the barriers 53, 5S so that -upon such insertion,the two blocks are moved relatively apart and the board is clampedbetween the two sets of ibearing surfaces. The contact portions of thecontacts lare, as with the previous embodiment, moved relatively intothe planes dened by the bearing surfaces so that again the amount offlexure `imparted to the contacts is controlled within precise limits.It will be apparent that the previously discussed advantages inure tothe embodiment `of FIGURES 6-10u The lstiffness of the springs `82 inthe embodiment of FIGURE 6 should again be sufficient to overcome thetotal force exerted by the contacts. If this relationship is maintained,the board will be clamped between the bearing surfaces 60 as shown inFIGURE 8 and will not be held merely by the contacts.

If desired, a block of the type shown alt Sil in FIGURE 6 can be usedwith 4a single sided panel of the type shown in FIGURES l-6. To achievethis modification (FIG- URE ll), a spring 96 is used having relativelylonger end portions 93 than the spring 80 and having reversely bent ends11%. -A flat panel 102 is interposed between the reversed ends 1% of thespring and the side 104 of the block so that this panel is normallyclamped against this side as shown in FIGURE yll. Upon insertion Iof theboard, the panel is moved relatively away from the s-urface 164 and theprinted circuit board is again clamped between the bearing surfaces ofthe barriers and the surface of the panel '102.

Changes in construction will occur to rthose skilled in the art andvarious apparently dilferent'modiiications and embodiments may be madeWithout departing from the scope of the invention. The matter set forthin the foregoing ydescription and accompanying dnawings is oifered byway of illustration only.

We claim:

l. An electrical connecting device for making disenlgageable electricalconnections with electrical conductors on a surface of a panel-likemember comprising, an insulating block, a plurality of contact membersmounted in said block, said contact members each having a contactportion for engagement with an electrical conductor on said panel-likemember said contact portions being disposed outwardly from one surfaceof said block Ibut being resilienitly movable towards said one surface,said block having a bearing surface ydisposed between said one surfaceand said contact portions, and clamping means on said block for clampingsaid panel-like member to said block, said clamping means comprising aclamping surface opposed to, and resiliently biased towards, `saidbearing surface whereby, upon insertion of said panel-like memberbetween said clamping surface and said contact portions of said contactmembers, said panel-like member is clamped against said bearing surfaceand said contact portions are resiliently flexed and displacedrelatively towards said one surface and into the plane of said bearingsurface, said contact portions being resiliently biased against saidconductors on said surface of said panel-like member as a result oftheir being iiexed, whereby the mechanical securement of said panel-likemember to said block is maintained independently of the electricalcontact between said contact portions and said conductors.

2. An electrical connecting device for making disengageable electricalconnections with the electrical conductors on a panel-like membercomprising, an insulating block, a plurality of contact members in saidblock, each contact member having a contact portion for engagement withone of said conductors, said contact portions being normally inlalignment with each other lalong a line which is spaced from oneysurface of said block, said contact portions beinrg resiliently movabletowards said one surface,V at least one ledge on said one surface, saidledge having a bearing surface which is spaced from said one surface andis disposed between said one surface and said line defined by sai-dcontact portions when in their normal positions, and clamping means forholding said panel-like member against said bearing surface, saidclamping means comprising a clamping surface opposed to, andr-esiliently biased towards, said bearing surface whereby, upon assembly'of said panel-like member to said block, said contact portions areresiliently moved relatively towards said surface and resiliently urgedagainst said conductors on said panel-like member, and said panel-likemember is clamped against said bearing surface and in assembledrelationship to said block by said clamping means, said panel-likemember being clamped to said block 4independently of said contactpontions and said conductors.

3. Apparatus as set forth in claim` 2 wherein said block `is providedwith a plurality of ledges in spaced apart relationship @and each ledgeprovides a bearing surface, said bearing surfaces lying in a singleplane, and said contacts are disposed in the cavities between adjacentledges.

4. Apparatus as set forth in claim 2 wherein said block has a trough forreception of said panel-like member, one of the sidewalls of said troughconstituting said one surface, and wherein said clamping means isdisposed in Said trough.

5. Apparatus as set forth in claim 2 wherein said block comprises twosections, each of said isections having a plurality of contact memberstherein, the contact members of each seotion being in alignment, eachsection having a bearing surface for bearing engagement with saidpanel-like member, and resilient means biasing said blocks towards eachother whereby, upon insertion of said panellike member between saidsections, said member is clamped between said bearing surfaces and saidcontacts are resiliently pressed against conducting paths on saidmember.

6. Apparatus as set forth in claim 2 wherein lsaid block comprises apair of substantially similar sections, each of said sections having arecess extending inwardly from two adjacent sides thereof, said sectionsbeing disposed against each other with said recesses juxtaposed todefine a troughlike opening for reception of said panel-like member,each of said sections having a battery of said contact members extendinginto its respective recess and each having at least one bearing surfacein its recess, and resilient means biasing said sections against eachother whereby, upon insertion of said panel-like member into saidtrough-like opening, said panel-like member is clamped between saidbearing surfaces and said contact members are resiliently pressedagainst conducting paths on said panel-like meniber.

7. An electrical connecting device for making disengageable electrical`connections with electrical conductors on a surface of a panel-likemember comprising, an insulating block, :a trough in said block forreception of an edge portion of said panel-like member, a plurality ofbarriers on one of the longitudinal sidewalls of `said trough,electrical contact members in said block having end portions extendinginto said trough and into the spaces between said barriers, said endportions having contact surface portions for engagement with 'conductorson said panel-like member, said end portions being resiliently movabletowards said one sidewall, said barriers being disposed betwen said onelongitudinal sidewall and said contact surface portions, and aresiliently biased clamping plate disposed in said trough and facingsaid barriers,

and spring means normally biasing said plate ltowards said mounted ineach of said sections Iand having end portions extending betweenadjacent barriers, contact portions on said end portions, and saidcontact portions of each siection being in alignment and bein-g`disposed inwardly of said trough with respect to said barriers whereby,upon insertion of said panel-like member intok said trough, said boardis clamped by said resilient means between the barriers of saidsidewalls, and said contact portions are resiliently engaged with theconductors on said member.

`9. In combination with la panel-like memlber having electricalconductors on both sides thereof, an electrical connecting deviceestablishing electrical contact with said conductors comprising, aninsulating block having a trough, an edge portion of said blockextending into said trough, said block being divi-ded into two sectionsalong a plane extending longitudinally through said trough, the

opposed longitudinal sidewalls of said trough having spaced barriersthereon, resilient means biasing said sections towards each other andagainst `said panel-like member thereby to clamp said block and membertogether, electrical contact-members mounted in each of said sectionsand having end portions extending between said barriers, said contactsbeing resiliently stressed by said panellike member and having contactportions in engagement with said conductors.

References Cited in the file of this patent UNiTED STATES PATENTS2,731,609 Sobel Ian. 17, 1956 2,857,577 Vanderpool Oct. 21, 19582,923,911 Demurjian Feb. 2, 1960 2,965,811 Batcher Dec. 20, 19602,968,016 Angelo Jan. 10, 1961 3,003,131 Nystuen Oct. 3, 1961 FOREIGNPATENTS 375,922 Great Britain July 7, 1932

1. AN ELECTRICAL CONNECTING DEVICE FOR MAKING DISENGAGEABLE ELECTRICALCONNECTIONS WITH ELECTRICAL CONDUCTORS ON A SURFACE OF A PANEL-LIKEMEMBER COMPRISING, AN INSULATING BLOCK, A PLURALITY OF CONTACT MEMBERSMOUNTED IN SAID BLOCK, SAID CONTACT MEMBERS EACH HAVING A CONTACTPORTION FOR ENGAGEMENT WITH AN ELECTRICAL CONDUCTOR ON SAID PANEL-LIKEMEMBER SAID CONTACT PORTIONS BEING DISPOSED OUTWARDLY FROM ONE SURFACEOF SAID BLOCK BUT BEEING RESILIENTLY MOVABLE TOWARDS SAID ONE SURFACE,SAID BLOCK HAVING A BEARING SURFACE DISPOSED BETWEEN SAID ONE SURFACEAND SAID CONTACT PORTIONS, AND CLAMPING MEANS ON SAID BLOCK FOR CLAMPINGSAID PANEL-LIKE MEMBER TO SAID BLOCK, SAID CLAMPING MEANS COMPRISING ACLAMPING SURFACE OPPOSED TO, AND RESILENTLY BIASED TOWARDS, SAID BEARINGSURFACE WHEREBY, UPON INSERTION OF SAID PANEL-LIKE MEMBER BETWEEN SAIDCLAMPING SURFACE AND SAID CONTACT PORTIONS OF SAID CONTACT MEMBERS,PANEL-LIKE MEMBER